Facility for heating a product in strip

ABSTRACT

A heating facility for strip product including a heating bed over which the strip travels and variable pressure devices which urge the strip toward the bed.

United States Patent Barny 1 June 13, 1972 [54] FACILITY FOR HEATING APRODUCT [56] References Cited IN STRIP UNITED STATES PATENTS [72]2,137,505 11/1938 Osgood ..144/282 [73] Assignee: Societe DEtudes et devante de Materiels 3,110,612 Ill 19 3 ttwa d t aL- -l /359 UX Pour I.Fabrication et le Faconnqe du 3,175,300 3/1965 Nitchie ..34/l44X CartonOndule-Martin, Rhone, France 3,489,063 1/1970 Piret ..91/466 X [22]Filed: May 1969 Primary Examiner-Carroll B. Dority, Jr. [211 App!823,123 Attorney-Cameron, Kerkam& Sutton 8 ABSTRACT [30] ForeignApplication Priority Data 1 A heating facility for stnp productincluding a heating bed May 10, 1968 France ..151405 over which thcstrip Have and variaue pressure devices which urge the strip toward thebed. [52] US. Cl ..34/43, 34/144, 38/8, 1 144/282 [51] Int. Cl .1F26b13/10 [58] Field of Search ..34/43, 56, 143, 144, 145; 6 Claims, 7Drawing Figures Dn'vz'rg Drum FKs'EPF'IEDJUH 13 19?? 3, 868 786 SHEET U0F 4 1 Way Solenoid Valve 52 33 w 55 Switch INVENTOR. fear Jacques BarngFACILITY FOR HEATING A PRODUCT IN STRIP This invention relates to animproved facility for heating a product in strip form which is movedover a heating surface, the facility being of use more particularly inthe heating section of the double-face portion of a corrugated cardboardmanufacturing machine.

The stuck-together assembly of smooth and curved sheets forming thecorrugated cardboard is heated in this part of the machine to dry thesheets and produce permanent adhesion between them. conventionally, thecardboard strip goes to this end over a number of iron or steel plateswhich are usually heated by an internal steam flow. An endless beltwhose bottom run bears on the cardboard strip keeps the same inengagement with the heating plates. The pressure applied by the belt tothe cardboard is amplified by idler rollers disposed freely inslide-ways or on pivoted levers so as to bear on the belt, the lattertherefore providing an at least rough distribu tion of their weight overthe cardboard strip.

The length of an installation of this kind is so devised that the dwellof the cardboard on the heating plates at the maximum speed of themachine is long enough for there to be a satisfactory heat exchangebetween the plates and the cardboard. However, when the speed has to bereduced for any reason, the dwell time of the cardboard increases and itoverheats. Because of the heat inertia of the heating-plate system, thetemperature of the plates cannot be varied rapidly in correlation withthe variations in the speed of strip movement.

Also, the normal practice is to use a single machine to corrugate boardshaving a very wide range of quality and comprcssive strength.Pressure-roller weight is calculated for working the heaviest andstrongest boards and is excessive for lightweight boards; to process thelatter, some of the rollers, for instance, one out of every two, must becut out to reduce the overall pressure, but this elimination does notreduce the local pressure of a roller on the board in the sameproportion.

To obviate these disadvantages, it is an object of this invention toenable the roller pressure on the board to be varied immediately andsteplessly. Another object of the inventionis to enable the heatexchange between the board and the heating plates to be varied withoutplate temperature having to be changed but by varying in dependence uponspeed the contact heatresistance transmission, by varying the contactpressure between the board and the plates.

According to the invention, each roller experiences its own weight plusthe action of at least one pressure-gas-energized ram. 7

The invention will now be described in greater detail with reference toan exemplary embodiment shown in the drawings wherein:

FIG. I is a partial simplified view of a double-face heating section ina conventional corrugating machine;

FIG. 2 shows a similar section but in accordance with the invention;

FIG. 3 shows simultaneous manual and servomotor control of a ram supplyexpander; and

FIG. 4 is a block diagram showing how such a servomotor can becontrolled;

FIG. 5 is a view similar to that of FIG. 2 showing solenoid actuatedvalves for energizing the rams;

FIG. 6 is a view similar to that of FIG. 2 showing cam actuated switchesfor the solenoid valves; and

FIG. 7 is a view similar to thatof FIG. 2 showing double acting rams andtwo way solenoid valves for energizing the rams.

Referring now to FIG. 1, a conventional heating section of a corrugating machine comprises a bearing frame in the form of longitudinalmembers I and ground support legs 2. Disposed transversely on members 1are heating plates 3 to which piping (not shown) for the supply of a hotfluid, such as steam, is connected. A corrugated cardboard strip 4 ismoved in the direction indicated by an arrow 5 by elements disposeddownstream of the zone shown and rests on plates 3. The endless belt 6is shown in FIG. 1 and passes over driving drum 50 and drum 5] as iswell known in the art; the width of belt 6 is equal to or greater thanthe width of the strip 4. Idler rollers 7, whose length is equal to orslightly greater than the width of the belt 6, are mounted at each endto rotate freely, in the ends of rods 8 connected by way of a pivot 9 toan auxiliary longitudinal member 10.

Referring to FIG. 2, which shows a similar portion of a corrugatingmachine but devised in accordance with the invention, presser rollers 11are disposed at the end of links 12 pivoted by way of pivots 13 on a topauxiliary longitudinal member 14. Each of pneumatic rams 15 has itscasing articulated to member 14 by way of a pivot 16 and its rodconnected by way of a pivot 17 to the respective links 12 and isenergized through a flexible pipe 18 connected to a general air line 19.

Referring now to FIG. 3, a pneumatic control valve 20 to whichcompressed air is supplied through a line 21 energizes the ramdistribution line 19 at a controlled pressure. Valve 20 has an adjustingrod which is connected to a combined servomotor and reducer 22 viagearwheel 23, an annulus 24 and satellites 25-27 of a planetary gearsystem, and gearwheels 28, 29. Satellite carrier arm 30 is rigidlysecured to a manual adjustment spindle 31 having a calibrated dial 32.Spindle 31 has known locking means (not shown) for immobilizing the arm30 when the same is not being used for manual adjustment. Apotentiometer 33 is disposed on the same shaft as the gearwheel 28.

Referring to FIG. 4, the servomotor 22 is connected to a power supply 40via a reversing contactor 41. The strip 4 is driven by a motor 42 havingmounted on the end of its shaft a tachometer dynamo 43 which delivers avoltage proportional to the speed of strip movement. The two voltagesproduced by the dynamo 43 and potentiometer 33 are input to anelectronic voltage comparator 44. Depending upon the sign of thedifference between the two voltages, comparator 44 outputs a signalwhich operates contactor 41 one way or the other, either via amplifier45 and relay 47 or via amplifier 46 and relay 48.

In a machine thus devised, when the speed of the strip 4 increases thevoltage produced by the dynamo 43 also increases and the regulator 44starts the servomotor 22 to the hand corresponding to an increase in thepneumatic pressure in the rams 15, until the potentiometer 33 connectedto the servomotor 22 has restored the balance between the voltages.Increasing the pressure in the rams 15 increases the pressure with whichthe cardboard 4 bears on the plates 3, and the correspondingly increasedheat transfer therefrom to the cardboard 4 compensates for the reductionof the dwell time of the cardboard 4 on the plates 3.

The range of pressure variation in the rams 15 can be altered by meansof the manual control to cope with different board qualities andstrengths. Action on the spindle 31 causes, via the satellites 26, analteration of the initial compressed air pressure delivered by the valve20 without altering the position of the potentiometer 33.

The invention is not of course limited by the exemplary embodimenthereinbefore described. For instance, placing the rams the opposite wayround as compared with the description falls under this invention, theforce which the rams produce then opposing the weight of the rollers. Anincrease in machine speed would then be associated with a gradualreduction of the air pressure in the rams, such pressure vanishing whenthe machine was running at maximum speed.

Also, a solenoid valve 52 (FIG. 5) can be provided in the supply line toeach group of two rams associated with a roller so that the rams actonly on some of the rollers. The number of rollers affected is selectedby manual operation of switches 53 controlling the energizing solenoidvalves. If required, the number of rollers with and without ram loadingcan be varied automatically by the switches of the solenoid valves beingoperated by an appropriately shaped cam 54 (FIGS. 3 and 6) driven by aservomotor of the same kind as used for the valve, such servomotor beingconnected to a similar strip-speed-dependent regulating facility.

Another possibility would be to use double-acting rams 55 (F IG. 7)combined with reversing solenoid valves 56 actuated by twolway switches57, in which event the rollers could have a weight greater than or lessthan their self-weight.

I claim:

1. A facility for heating a product in strip form comprising a heatingsurface over which thestrip is movable and means for maintaining thestrip in contact therewith, said means including a continuous beltloaded by evenly spaced idler rollers, each roller exerting on said beltits own weight and at least one I pressure-gas-energized ram connectedto each of said rollers to increase the load on said belt, said ramsbeing pressurefluid-energized, at least one valve controlling the fluidpressure to said rams, a servomotor controlling said valve andregulating means controlling said servomotor receiving informationrelating-to the speed of strip movement and information relating to theposition of said servomotor.

2. A facility as set forth in claim 1, said regulating means including avoltage comparator receiving a first voltage, a tachometer dynamo drivenat a speed proportional to strip speed providing said first voltage, andreceiving a second voltage, and a potentiometer associated with theposition of said servomotor providing said second voltage.

3. A facility as set forth in claim 2, said valve including a manualcontrol facility independent of the servomotor control, the two controlsbeing usable simultaneously.

' 4. A facility as set forth in claim 1, including a solenoid actuatedvalve for said rams associated with a single roller. and a switch foreach of said solenoid actuated valves.

5. A facility as set forth in claim 4, said switches being controlled bya cam, a servomotor rotating said cam and regulating means for saidservomotor receiving information relating to the speed of stripmovement.

6. A facility as set forth in claim 4, said rams being dou bleacting andsaid solenoid valves being reversible.

I 1 n I:

1. A facility for heating a product in strip form comprising a heating surface over which the strip is movable and means for maintaining the strip in contact therewith, said means including a continuous belt loaded by evenly spaced idler rollers, each roller exerting on said belt its own weight and at least one pressure-gas-energized ram connected to each of said rollers to increase the load on said belt, said rams being pressure-fluidenergized, at least one valve controlling the fluid pressure to said rams, a servomotor controlling said valve and regulating means controlling said servomotor receiving information relating to the speed of strip movement and information relating to the position of said servomotor.
 2. A facility as set forth in claim 1, said regulating means including a voltage comparator receiving a first voltage, a tachometer dynamo driven at a speed proportional to strip speed providing said first voltage, and receiving a second voltage, and a potentiometer associated with the position of said servomotor providing said second voltage.
 3. A facility as set forth in claim 2, said valve including a manual control facility independent of the servomotor control, the two controls being usable simultaneously.
 4. A facility as set forth in claim 1, including a solenoid actuated valve for said rams associated with a single roller, and a switch for each of said solenoid actuated valves.
 5. A facility as set forth in claim 4, said switches being controlled by a cam, a servomotor rotating said cam and regulating means for said servomotor receiving information relating to the speed of strip movement.
 6. A facility as set forth in claim 4, said rams being double-acting and said solenoid valves being reversible. 